Which function is shown in the graph below ?

a. y=log0.4x

b. y=log1x

c. y=log3x

d. y=log10x

It has been given that the point (3,1) is on the graph. For the point (3,1) to be on the graph, the following must hold true:

or

Thus,

Thus, in order for the point (3,1) to lie on the graph, of all the given options the closest we can get is when we have Option C, that is, when a=3. That will make x=3.33 and thus, .

Thus, out of the given options only Option C seems to be the most probable answer.